key DODGE NEON 1999 Service Manual PDF

CAV CIRCUIT FUNCTION
1 M2 20YL* DOOR LIFT GROUND SWITCH
2 G34 16RD/GY HIGH BEAM INDICATOR DRIVER
2 L3 16RD/OR** DIMMER SWITCH HIGH BEAM OUTPUT
3 L60 22TN RIGHT TURN SIGNAL
4 G10 20LG/RD SEAT BELT SWITCH SENSE
5 G5 20DB/WT FUSED IGNITION SWITCH OUTPUT (ST-RUN)
6 M1 22PK FUSED B(+)
7 G21 22GY/LB TACHOMETER SIGNAL
8 Z3 16BK/OR GROUND
9 R41 18BK/TN AIRBAG WARNING LAMP DRIVER
10 G7 22WT/OR VEHICLE SPEED SENSOR SIGNAL
BLACK
51
10 6
** RKE
CAV CIRCUIT FUNCTION
1 G6 22GY OIL PRESSURE SWITCH SENSE
2 G19 22LG/OR ABS WARNING LAMP DRIVER
3 G3 22BK/PK CHECK ENGINE LAMP DRIVER
4 G20 22VT/YL ECT GAUGE SENSOR SIGNAL
5 G26 20LB KEY-IN IGNITION SWITCH SENSE
6 G9 22GY/BK RED BRAKE WARNING LAMP DRIVER
7 G12 22TN/BK GENERATOR LAMP DRIVER
8 L61 22LG LEFT TURN SIGNAL
9 E2 22OR PANEL LAMPS DRIVER
10 G4 20DB FUEL LEVEL SENSOR SIGNAL
BLACK
51
10 6
INSTRUMENT
CLUSTER - C1
CLUSTER - C2INSTRUMENT
* LHD
8W - 80 - 24 8W-80 CONNECTOR PIN-OUTSPL
J988W-1PL008024

CAV CIRCUIT FUNCTION
A K4 18BK/LB SENSOR GROUND
B K21 20BK/RD INTAKE AIR TEMPERATURE SENSOR SIGNAL
C K6 18VT/WT 5 VOLT SUPPLY
D K1 20DG/RD MAP SENSOR SIGNAL BLACK
AD
CAV CIRCUIT FUNCTION
1 G16 20BK/LB LEFT FRONT DOOR JAMB SWITCH SENSE
2 G26 20LB KEY-IN IGNITION SWITCH SENSE
GREEN
21
CAV CIRCUIT FUNCTION
1 K42 20DB/LG* KNOCK SENSOR SIGNAL
1 K42 20BK/LG** KNOCK SENSOR SIGNAL
2 K4 20BK/LB SENSOR GROUND
** 2.0L DOHC* 1.8L/2.0L SOHC
CAV CIRCUIT FUNCTION
1 R47 18DB/LB LEFT IMPACT SENSOR LINE 1
2 R49 18LB LEFT IMPACT SENSOR LINE 2
BLACK
21
GRAY
21
CAV CIRCUIT FUNCTION
1 Z1 18BK GROUND
2 L1 18VT/BK BACK-UP LAMP SENSE
1
BLACK
2
CAV CIRCUIT FUNCTION
1 Z2 22BK/LG GROUND
2 V5 18DG/YL WIPER RELAY COMMON
3 V10 18BR WINDSHIELD WASHER RELAY OUTPUT
4 V3 18BR/WT WIPER SWITCH LOW SPEED OUTPUT
5 F13 18DB FUSED IGNITION SWITCH OUTPUT (RUN-ACC)
6 V4 18RD/YL WIPER SWITCH HIGH SPEED OUTPUT
NATURAL
61
INTAKE AIR
TEMPERATURE/MANIFOLD
ABSOLUTE PRESSURE
(IAT/MAP)
SENSOR
INTERMITTENT
WIPE/WASH
SWITCH
KEY-IN
SWITCH
KNOCK
SENSOR
LEFT AIRBAG
IMPACT SENSOR
LEFT BACK-UP
LAMP
(EXCEPT BUILT-UP-EXPORT)
PL8W-80 CONNECTOR PIN-OUTS 8W - 80 - 25
PL008025J988W-1

CAV CIRCUIT FUNCTION
1 E2 220R FUSED PANEL LAMPS DIMMER SWITCH SIGNAL
2 Z2 22BK/LG GROUND
3 F20 22WT FUSED IGNITION SWITCH OUTPUT (RUN)
4 A4 14BK/RD FUSED B(+)
5 C15 14BK/WT REAR WINDOW DEFOGGER RELAY OUTPUT
BLACK
51
41
85
CAV CIRCUIT FUNCTION
1 P34 16PK/WT DOOR UNLOCK DRIVER
2 F35 16RD/YL FUSED B(+)
3 Z2 22BK/LG GROUND
4 D9 20DG RKE PROGRAM ENABLE
5 L4 14VT/WT DIMMER SWITCH LOW BEAM OUTPUT
6 M23 22YL/BK TIME DELAY RELAY
7 M1 22PK FUSED B(+)
8 G5 20DB/WT FUSED IGNITION SWITCH OUTPUT (ST-RUN)
BLACK
41
85
CAV CIRCUIT FUNCTION
1 P35 16OR/WT LEFT DOOR LOCK SWITCH OUTPUT
2 P36 16PK/VT LEFT DOOR UNLOCK SWITCH OUTPUT
3 P36 16PK/LB LEFT DOOR UNLOCK SWITCH OUTPUT
4 P35 16OR/VT LEFT DOOR LOCK SWITCH OUTPUT
5 L7 20BK/YL PARK LAMP SWITCH OUTPUT
6 X3 20BK/RD HORN RELAY CONTROL
7- -
8 P34 16PK/BK DOOR UNLOCK DRIVER
GRAY
8FRONT FOG LAMP FEED L35 20BR/RD 7
FUSED ILLUMINATION FEED E2 20OR 6
GROUND Z3 20BK/OR 5
HEADLAMP SWITCH FEED L2 14LG 4
REAR FOG LAMP FEED L38 18BR/WT 3
FOG LAMP FEED F61 18WT/OR 2
- - 1
FUNCTION CIRCUIT CAV
- - Z3 20BK/OR GROUND
5
8 1
NATURAL
REAR FOG
LAMP SWITCH
REAR WINDOW
DEFOGGER SWITCH
REMOTE KEYLESS
ENTRY (RKE)
MODULE - C1
REMOTE KEYLESS
ENTRY (RKE)
MODULE - C2 (BUILT-UP-EXPORT)
8W - 80 - 36 8W-80 CONNECTOR PIN-OUTSPL
J988W-1PL008036

Connector
Name/NumberColor Location Fig.
Daytime Running
Lamp ModuleBK Rear of Radio 15
Dome Lamp BK LT C-Pillar 20
Downstream
Heated Oxygen
SensorBK RT Rear of
EngineN/S
Driver Side
AirbagYL Rear of
Clockspring12
Duty Cycle
Evap/Purge
SolenoidGY RT Strut Tower 5
Engine Coolant
Temp SensorBK LT Side of
Cylinder Head8
EGR Solenoid GY LT Rear of
Cylinder Head8
Engine Starter
MotorLeft Front of
Engine9
Fog Lamp
SwitchBK Rear of Switch 16
Fuel Injector #1 BK At Injector 9
Fuel Injector #2 BK At Injector 9
Fuel Injector #3 BK At injector 9
Fuel Injector #4 BK At Injector 9
Fuel Pump
ModuleLT/GY At Module 23
Fuse Block Left Side of
Instrument
Panel17
G101 Top LT of
Radiator Closure
Panel6
G102 Top LT of
Radiator Closure
Panel6
G103 RT Radiator
Closure Panel5
G104 Front Lower of
EngineN/S
G105 Front of Battery 6
G110 Right Radiator
Closure Panel5
G201 RT Side of I.P.
Center Stack15
G202 RT Side of I.P.
Center Stack15
G203 LT Side of I.P.
Center Stack15
Connector
Name/NumberColor Location Fig.
G204 LT Side of I.P.
Center Stack15
G301 RT Rear Quarter
Panel24
G302 LT Rear Quarter
Panel24
G303 LT Rear Quarter
Panel24
Generator BK Rear of
Generator8
Glove Box Lamp
and SwitchBK Rear of Switch 16
Headlamp
Dimmer/Optical
Horn SwitchBK Rear of Switch 12
Headlamp
SwitchBK Bottom of
Switch14
Heater Blower
MotorBK RT Side of
HVAC HousingN/S
Horn BK LT Inner Fender 7
Horn #2 (BUX) BK Right Inner
FenderN/S
Headlamp
Leveling SwitchBK Left Side of I.P. N/S
Immobilizer Behind Center
StackN/S
Immobilizer
Engine SensorLeft Kick Panel N/S
Idle Air Control
MotorBK On Throttle
Body9
Ignition Coil
PackBK Top of Valve
Cover8
Ignition Switch GY Rear of Switch 12
Halo Lamp BK At Lamp N/S
Instrument
Cluster C1BK LT Side of
Cluster17
Instrument
Cluster C2BK RT Side of
Cluster15
Intake Air
Temp/MAP
SensorBK RT Side of
Intake9
Key-In Switch GN Rear of Switch 12
Knock Sensor GY Front of Engine 9
Left Back-Up
LampGY At Lamp 24
8W - 90 - 2 8W - 90 CONNECTOR/GROUND LOCATIONSPL
DESCRIPTION AND OPERATION (Continued)

Connector
Name/NumberColor Location Fig.
Driver Door Lock
SwitchWT At Switch 18
Left Front Door
SpeakerBK At Speaker 18
Drivers Power
Window MotorBK At Motor 18
Left Fog Lamp BK At Lamp 5
Drivers Door
Lock MotorGY At Motor 18
Left Front Side
Marker LampNAT At Lamp 7
Left Front Wheel
Speed SensorGY LT Fender Side
Shield3
Left Headlamp BK At Lamp 7
Left Instrument
Panel SpeakerBK At Speaker 15
Left Park/Turn
Signal LampBK At Lamp 7
Left Power Mirror GY At Mirror 18
Left Headlamp
Leveling MotorBK Rear of Left
HeadlampN/S
Left Repeater
LampLeft Fender N/S
Left Rear Fog
LampBK At Lamps N/S
Left Rear Door
Lock MotorBK At Motor 19
Left Rear
SpeakerBK At Speaker 20
Left Rear Wheel
Speed SensorGY LT Rear Frame
RailN/S
Left Tail/Stop/
Turn Signal
LampBK At Lamp 24
License Plate
LampNAT Rear of Lamp 22
Map/Reading
LampsBK Front of
Windshield
Header11
Driver Power
Window SwitchBK At Switch 18
Engine Oil
Pressure SwitchGN Rear of Engine 8
Park/Neutral
Position SwitchBK Front of
Transmission4
Passenger Side
Airbag SquibYL Rear of PAB 16
Connector
Name/NumberColor Location Fig.
Power Mirror
SwitchBK At Switch 18
Power Sunroof
MotorRD At Motor 11
Power Steering
Pressure SwitchGY LT Side of
Steering Gear6
Powertrain
Control Module
C1BK LT Fender Side
Shield6
Powertrain
Control Module
C2BK LT Fender Side
Shield6
Power
Distribution
CenterLeft Front
Engine
Compartment6
PRNDL Lamp BK Base of
Gearshift13
Radiator Fan
MotorBK Rear of Motor 7
Radio C1 BK Rear of Radio 15
Radio C2 GY Rear of Radio 15
Rear Window
Defogger SwitchBK Rear of Switch 16
Remote Keyless
Entry Module C1BK At Module N/S
Remote Keyless
Entry Module C2LT/GY At Module N/S
Rear Fog Lamp
SwitchNAT In Center Stack N/S
Right Repeater
LampRight Fender N/S
Right Rear Fog
LampBK At Lamp N/S
Right Back-Up
LampGY At Lamp 24
Passenger Door
Lock SwitchWT At Switch 18
Passenger Door
Power Window
SwitchWT At Switch 18
Passenger Door
Window Lift
MotorBK At Motor 18
RIght Fog Lamp BK At Lamp 5
Right Front Door
SpeakerBK At Speaker 18
PL8W - 90 CONNECTOR/GROUND LOCATIONS 8W - 90 - 3
DESCRIPTION AND OPERATION (Continued)

Connector
Name/NumberColor Location Fig.
Engine Coolant
Temp SensorBK Left Side of
Engine7
Engine Oil
Pressure SwitchGN Rear Of Engine 7
Engine Starter
MotorLeft Front of
Engine7
EGR
Transducer
SolenoidGY Left Rear of
Engine7
Fog Lamp
SwitchGN Rear of Switch 14
Fuel Injector #1 BK At Injector 8
Fuel Injector #2 BK At Injector 8
Fuel Injector #3 BK At injector 8
Fuel Injector #4 BK At Injector 8
Fuel Pump
ModuleLT/GY Right Rear
Frame Rail19
Fuse Block Right Side of
I.P.N/S
G101 Top Left of
Radiator
Closure Panel5
G102 Top Left of
Radiator
Closure Panel5
G103 Right Radiator
Closure Panel4
G104 Front Lower of
EngineN/S
G105 Front of Battery 5
G201 Left Side of I.P.
Center Stack13
G202 Left Side of I.P.
Center Stack13
G203 Right Side of
I.P. Center
Stack13
G204 Right Side of
I.P. Center
Stack13
G301 Right Rear
Quarter Panel20
G302 Left Rear
Quarter Panel20
G303 Left Rear
Quarter Panel20Connector
Name/NumberColor Location Fig.
Generator GY Rear of
Generator7
Glove Box
Lamp and
SwitchBK Rear of Switch 13
Headlamp
Dimmer and
Optical Horn
SwitchBK Rear of Switch 12
Headlamp
Leveling SwitchBK Rear of Switch 14
Headlamp
SwitchBK Rear of Switch 14
Horn #1 BK LT Inner Fender 6
Horn #2 BK Right Inner
FenderN/S
Idle Air Control
MotorBK On Throttle
Body8
Ignition Coil
PackBK Top of Valve
Cover7
Ignition Switch GY Rear of Switch 10
Immobilizer
Engine SensorBK Left Fender
Side ShieldN/S
Immobilizer BK Behind Center
StackN/S
Instrument
Cluster C1BK Rear of Cluster 14
Instrument
Cluster C2BK Rear of Cluster 14
Intake Air
Temp/MAP
SensorBK Left Side of
Intake8
Halo Lamp BK At Lamp N/S
Key-In Switch GN Rear of Switch 10
Knock Sensor GY Front of Engine 8
Left Back-Up
LampGY At Lamp 20
Passenger Door
Lock SwitchWT At Switch 12
Passenger Door
Lock SwitchBK At Motor 12
Left Door
SpeakerBK At Speaker 18
Left Door
Window Lift
MotorBK At Motor 18
Left Fog Lamp BK At Lamp 4
8W - 90 - 24 8W - 90 CONNECTOR/GROUND LOCATIONSPL
DESCRIPTION AND OPERATION (Continued)

Connector
Name/NumberColor Location Fig.
Passenger
Power Door
Lock MotorGY At Motor 12
Left Front
Wheel Speed
SensorGY Left Fender
Side ShieldN/S
Left Headlamp BK At Lamp 6
Left Headlamp
Leveling MotorBK Rear of Left
HeadlampN/S
Left Instrument
Panel SpeakerBK At Speaker 13
Left License
LampNAT At Lamp N/S
Left Park/Turn
Signal LampBK At Lamp 6
Left Power
MirrorGY At Mirror 12
Passenger
Power Window
MotorWT At Switch 12
Left Rear Door
Lock MotorBK Rear of Door 15
Left Rear Fog
LampBK At Lamp N/S
Left Rear
SpeakerBK At Speaker 16
Left Rear Wheel
Speed SensorBK Left Rear
Frame RailN/S
Left Repeater
LampBK At Lamp N/S
Left Tail/Stop
Signal LampBK At Lamp 20
Left Turn Signal
LampNAT At Lamp N/S
Map/Reading
LampsBK At Lamps 9
Drivers Power
Window SwitchBK At Switch 12
Park/Neutral
Position SwitchBK Front of
Transmission3
Passenger Side
AirbagYL Left Side of I.P. 13
Power
Distribution
CenterLeft Front
Engine
Compartment5
Power Folding
Mirror RelayBK At Switch 18Connector
Name/NumberColor Location Fig.
Power Mirror
Fuse HolderGY Near Power
MirrorN/S
Power Mirror
Switch C1BK At Switch 12
Power Mirror
Switch C2WT At Switch 12
Power Steering
Pressure SwitchGY Rear of
Steering Gear5
Power Sunroof
MotorRD At Motor 9
Powertrain
Control Module
C1BK Left Fender
Side Shield5
Powertrain
Control Module
C2BK Left Fender
Side Shield5
PRNDL Lamp BK Rear of
Gearshift11
Radiator Fan
MotorBK Rear of Fan 6
Radio C1 BK Rear of Radio 13
Radio C2 GY Rear of Radio 13
Rear Fog Lamp
SwitchBK At Switch N/S
Rear Window
Defogger SwitchBK Rear of Switch 13
Remote Keyless
Entry Module
C1BK At Module N/S
Remote Keyless
Entry Module
C2LT/GY At Module N/S
Right Back-Up
LampGY At Lamp 20
Driver Door
Lock SwitchWT At Switch 12
Driver Power
Window SwitchBK At Motor 12
RIght Fog Lamp BK At Lamp 4
Driver Door
Lock MotorBK At Motor 12
Right Front
Door SpeakerBK At Speaker 12
Right Front
Wheel Speed
SensorGY Right Fender
Side Shield4
Right Headlamp BK At Lamp 4
PL8W - 90 CONNECTOR/GROUND LOCATIONS 8W - 90 - 25
DESCRIPTION AND OPERATION (Continued)

DIAGNOSIS AND TESTING
FUEL PUMP PRESSURE TEST
The fuel system operates at approximately 338 kPa
(49 psi). Check fuel system pressure at the test port
on the fuel rail (Fig. 7).
(1) Remove cap from fuel pressure test port on fuel
rail.
(2) Connect Fuel Pressure Gauge C-4799B to test
port (Fig. 8).CAUTION: When using the ASD Fuel System Test,
the ASD relay and fuel pump relay remain energized
for 7 minutes or until the test is stopped, or until
the ignition switch is turned to the Off position.
(3) Place the ignition key in the ON position.
Using the DRB scan tool, access ASD Fuel System
Test. The ASD Fuel System Test will activate the fuel
pump and pressurize the system.
²If the gauge reading equals 338 kPa (49 PSI)
further testing is not required. If pressure is not cor-
rect, record the pressure.
²If fuel pressure is below specifications, refer to
the Fuel Pressure Diagnosis Chart (Fig. 9).
²If fuel pressure is above specifications (54 psi or
higher) check for a kinked or restricted fuel supply
line. If the supply line is not kinked or restricted,
replace the Fuel Filter/Pressure Regulator.
(4) Replace Pressure test port cap when finished
doing pressure test.
FUEL LEVEL SENSOR
This procedure tests the resistance of the level sen-
sor itself. It does not test the level sensor circuit.
Refer to Group 8W - Wiring Diagrams for circuit
identification.
The level sensor is a variable resistor. Its resis-
tance changes with the amount of fuel in the tank.
The float arm attached to the sensor moves as the
fuel level changes. To test the level sensor, connect
an ohmmeter across the sensor signal and sensor
ground terminals of the fuel pump module connector
(Fig. 10). Move the float lever to the positions shown
in the resistance chart (Fig. 10). Record the resis-
tance at each point. Replace the level sensor if the
resistance is not within specifications.
Fig. 8 Checking Fuel Pressure at Intake ManifoldÐ
Typical
Fig. 6 Plastic Quick-Connect Fittings
Fig. 7 Fuel Pressure Test PortÐTypical
14 - 6 FUEL SYSTEMPL
DESCRIPTION AND OPERATION (Continued)

GENERAL INFORMATION
INTRODUCTION
All engines used in this section have a sequential
Multi-Port Electronic Fuel Injection system. The MPI
system is computer regulated and provides precise
air/fuel ratios for all driving conditions. The Power-
train Control Module (PCM) operates the fuel injec-
tion system.
The PCM regulates:
²Ignition timing
²Air/fuel ratio
²Emission control devices
²Cooling fan
²Charging system
²Idle speed
²Vehicle speed control
Various sensors provide the inputs necessary for
the PCM to correctly operate these systems. In addi-
tion to the sensors, various switches also provide
inputs to the PCM.
All inputs to the PCM are converted into signals.
The PCM can adapt its programming to meet chang-
ing operating conditions.
Fuel is injected into the intake port above the
intake valve in precise metered amounts through
electrically operated injectors. The PCM fires the
injectors in a specific sequence. Under most operat-
ing conditions, the PCM maintains an air fuel ratio
of 14.7 parts air to 1 part fuel by constantly adjust-
ing injector pulse width. Injector pulse width is the
length of time the injector is open.
The PCM adjusts injector pulse width by opening
and closing the ground path to the injector. Engine
RPM (speed) and manifold absolute pressure (air
density) are the primary inputs that determine injec-
tor pulse width.
MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.
There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygen
sensor diagnostics (they are checked for shorted con-
ditions at all times).During CLOSED LOOP modes the PCM monitors
the inputs from the upstream and downstream
heated oxygen sensors. The upstream heated oxygen
sensor input tells the PCM if the calculated injector
pulse width resulted in the ideal air-fuel ratio of 14.7
to one. By monitoring the exhaust oxygen content
through the upstream heated oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation,
the following must occur:
(1) Engine coolant temperature must be over 35ÉF.
²If the coolant is over 35É the PCM will wait 44
seconds.
²If the coolant is over 50ÉF the PCM will wait 38
seconds.
²If the coolant is over 167ÉF the PCM will wait
11 seconds.
(2) For other temperatures the PCM will interpo-
late the correct waiting time.
(3) O2 sensor must read either greater than .745
volts or less than .1 volt.
(4) The multi-port fuel injection systems has the
following modes of operation:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
(5) The engine start-up (crank), engine warm-up,
deceleration with fuel shutoff and wide open throttle
modes are OPEN LOOP modes. Under most operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
PCM determines basic fuel injector pulse width from
this input.
²The PCM determines atmospheric air pressure
from the MAP sensor input to modify injector pulse
width.
When the key is in the ON position and the engine
is not running (zero rpm), the Auto Shutdown (ASD)
and fuel pump relays de-energize after approximately
1 second. Therefore, battery voltage is not supplied to
the fuel pump, ignition coil, fuel injectors and heated
oxygen sensors.
PLFUEL SYSTEM 14 - 21

As Intake Air temperature varies the Intake Air
Temperature sensors resistance changes resulting in
a different input voltage to the PCM.
The IAT sensor and Manifold Absolute Pressure
(MAP) switch are a combined into a single sensor
that attachs to the intake manifold (Fig. 13) or (Fig.
14).
KNOCK SENSORÐPCM INPUT
The knock sensor threads into the side of the cyl-
inder block in front of the starter (Fig. 15). When the
knock sensor detects a knock in one of the cylinders,
it sends an input signal to the PCM. In response, the
PCM retards ignition timing for all cylinders by a
scheduled amount.
Knock sensors contain a piezoelectric material
which sends an input voltage (signal) to the PCM. As
the intensity of the engine knock vibration increases,
the knock sensor output voltage also increases.
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐPCM INPUT
The PCM supplies 5 volts direct current to the
MAP sensor. The MAP sensor converts intake mani-
fold pressure into voltage. The PCM monitors the
MAP sensor output voltage. As vacuum increases,
MAP sensor voltage decreases proportionately. Also,
as vacuum decreases, MAP sensor voltage increases
proportionately.
At key on, before the engine is started, the PCM
determines atmospheric air pressure from the MAP
sensor voltage. While the engine operates, the PCM
determines intake manifold pressure from the MAP
sensor voltage. Based on MAP sensor voltage and
inputs from other sensors, the PCM adjusts spark
advance and the air/fuel mixture.
The MAP/Intake Air Temperature sensor mounts to
the intake manifold (Fig. 13) and (Fig. 14).
Fig. 12 Downstream Heated Oxygen Sensor
Fig. 13 / MAP/Intake Air Temperature SensorÐSOHC
Fig. 14 MAP/Intake Air Temperature SensorÐDOHC
Fig. 15 Knock Sensor
PLFUEL SYSTEM 14 - 29
DESCRIPTION AND OPERATION (Continued)